The invention relates to an apparatus for the separation of sheets.
From practice, many types of apparatuses for the separation of sheets from a stack or from a mutually overlapping situation are known. In separation apparatuses comprising a circulating surface which presses against an outermost sheet or set of sheets with a normal force and exerts a force on the outermost sheet or the outermost set of sheets by means of frictional force in a direction of transport, the problem sometimes arises that the force exerted on the outermost sheet in the direction of transport cannot overcome the frictional forces occurring during the separation so that the sheet or the set of sheets is not taken from the stack but gets stuck in the area of the circulating surface.
This problem especially arises when the circulating surface which must exert the force in the direction of transport ages or soils and when sheets having very smooth but mutually adhering surfaces must be separated. Especially separation apparatuses processing printed and often soiled paper, for instance for the separation of originals in a fax or photocopier or for the separation of documents or enclosures in an enveloping apparatus, suffer from this problem.
As referred to herein, a set of sheets is two or more sheets which are connected or engaged with each other in any way (for instance because they have been folded together).
It is an object of the invention to increase the reliability of the separation of sheets or sets of sheets from a stack or at least a mutually overlapping situation by means of frictional forces exerted on an outermost sheet.
According to the present invention, this object is achieved by providing an apparatus for the separation of sheets including: a transport structure for exerting a force on an outermost sheet of a pack of sheets in a direction of transport substantially parallel to this sheet; and a separation structure for exerting a force on at least one other sheet of the pack against the direction of transport to prevent the at least one other sheet from moving along with the outermost sheet in the direction of transport, the sheets overlapping each other, at least the transport structure or the separation structure having a rough surface suspended for exerting a force with a normal force component transversely to the outermost sheet and a frictional force component parallel to the direction of transport; further including a treating device intended for treatment of the rough surface to increase the roughness of the rough surface.
Because the apparatus comprises a treating device for increasing the roughness of the circulating surface, the negative effect which soiling and aging have on the roughness can be counteracted and the roughness of the circulating surface can be kept at a higher level, especially over a longer period. This makes it possible to increase the operating reliability of the apparatus. Thus, for instance, the initial reliability can be increased because a deterioration of the roughness of the rollers during assembly and storage can be compensated at least partly. The reliability over a longer period can be increased because the deterioration of the roughness is limited or because the roughness is increased again from time to time. The invention further makes it possible by means of special treatments without manual intervention to bring the roughness to a level which without facilities for the treatment of the rough surface would lead to rapid soiling and a short life span of the rough surface.
Further objects, practical aspects, effects and details of the invention will appear from the following description in which a number of practical examples is described with reference to the drawing. Moreover, special practical aspects of the invention are laid down in the dependent claims.